Muir's corella (''Cacatua pastinator pastinator'') is a stocky, medium-sized white

cockatoo A cockatoo is any of the 21 species of parrots belonging to the family Cacatuidae, the only family in the superfamily Cacatuoidea. Along with the Psittacoidea ( true parrots) and the Strigopoidea (large New Zealand parrots), they make up t ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

. It was the

threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

nominate

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the

western corella The western corella (''Cacatua pastinator'') also known as the western long-billed corella, is a species of white cockatoo endemic to south-western Australia. Taxonomy Cacatuidae is one of three families of the large and diverse avian order Psit ...

.Anon. (2007). ''Muir’s Corella''. (Fauna Note No.4). Department of Environment and Conservation, Western Australi

/ref> It was removed from the WA's threatened species list in November 2012 as a result of successful conservation efforts.May (2012). ''Cockatoo, contentious moth back from brink''. Herald Sun
/ref>

Description

Muir's corella has mainly white

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

with an erectile white crest. The undersides of the wings and tail are yellow. The

feather Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and an exa ...

s between the eye and beak are deep salmon-pink, as are the bases of the feathers on the head and underparts. The eye is surrounded by a broad grey-blue eye-ring. The white feathers are often stained with soil because of the birds’

foraging Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...

activities. The corellas have a wingspan of 90 cm, and range from 43–48 cm in length and 560–815 g in weight. They have a variety of loud and raucous calls. They are very similar in appearance to

Butler's corella Butler's corella (''Cacatua pastinator butleri'') is a medium-sized white cockatoo endemism, endemic to Western Australia. It is one of two subspecies of the western corella.Anon. (2007). ''Butler’s Corella''. (Fauna Note No.19). Department of ...

, the only other subspecies of the western corella, being slightly larger with a longer upper mandible.

Distribution and habitat

Muir's corella formerly inhabited woodlands and open country east of the main area of forest in south-western Western Australia, occurring north to the

Swan Swans are birds of the genus ''Cygnus'' within the family Anatidae. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe (biology) ...

and Avon Rivers, south to Albany and Augusta, and eastwards to the

Stirling Stirling (; ; ) is a City status in the United Kingdom, city in Central Belt, central Scotland, northeast of Glasgow and north-west of Edinburgh. The market town#Scotland, market town, surrounded by rich farmland, grew up connecting the roya ...

and Porongurup Ranges. The birds were distributed in small, widely separated colonies throughout this range. However, the population has declined and the subspecies now only occurs in the

Lake Muir Lake Muir is a freshwater lake, with a larger surrounding wetlands area, that is located in the South West region of Western Australia. The lake lies near Muir Highway, north of Walpole and southeast of Manjimup. Description The lake has a ...

region where the remainder of the woodland habitat consists of fragmented remnants.

Behaviour

Muir's corellas are gregarious and may be seen in flocks of ten to a thousand birds. They have traditional roosting sites, usually in dense timber, which they leave in the morning for their feeding areas and return to at night.

Feeding

The corellas forage on the ground in large flocks and feed on a wide variety of seeds of both native and introduced plants, as well as

corm Corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen, underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat (perennation). The word ''c ...

s and tubers which they dig up using the elongated upper mandibles of their bills. Cereal grains, including oats, barley and wheat, are eaten extensively in summer and autumn, while the corms of onion grass are important in winter and spring.

Breeding

The corellas nest in

tree hollows A tree hollow or tree hole is a semi-enclosed cavity which has naturally formed in the trunk or branch of a tree. They are found mainly in old trees, whether living or not. Hollows form in many species of trees. They are a prominent feature of n ...

of large, mature

eucalypt Eucalypt is any woody plant with Capsule (fruit), capsule fruiting bodies belonging to one of seven closely related genera (of the tribe Eucalypteae) found across Australia: ''Eucalyptus'', ''Corymbia'', ''Angophora'', ''Stockwellia'', ''Allosyn ...

s, including

jarrah ''Eucalyptus marginata'', commonly known as jarrah, in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with rough, fibro ...

and marri. Eggs are laid from September to November with a clutch size of 1–3. The incubation period lasts 26–29 days until fledging. During the breeding season the birds feed close to the nest tree. After fledging, the young birds and their parents join other family groups to form large flocks that disperse to summer feeding areas. At the end of summer, breeding adults return to their nest sites while immature birds form nomadic flocks.

Status and conservation

Muir's corella is considered to be

because it consists of one relatively small and isolated population covering a fragmented range of about 3000 km², with the actual area of occupancy being about 500 km². It is listed as Vulnerable under Australia's

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

.Australian Government, Department of the Environment, Water, Heritage and the Arts - Species Profile and Threats Database: ''Cacatua pastinator pastinator'

/ref> Population estimates vary; it may comprise up to 9000 individuals, including only about 2500 mature birds,Garnett, Stephen T.; & Crowley, Gabriel M. (2000). ''The Action Plan for Australian Birds 2000''. Environment Australia: Canberra. having gradually recovered from a low of about 100 individuals in the 1940s after widespread shooting and poisoning in the late nineteenth and early twentieth centuries.''Muir’s Corella: conserving a threatened species''. Australian Government and South West Catchments Council. Average life expectancy of adults has been estimated at 17 years for males and 14 years for females, with most young birds dying before they reach breeding age of 3–5 years old. While current nest hollow and food availability are sufficient to sustain the population, changes in land use may threaten the corella where remnant vegetation and paddock trees are cleared to establish

plantation Plantations are farms specializing in cash crops, usually mainly planting a single crop, with perhaps ancillary areas for vegetables for eating and so on. Plantations, centered on a plantation house, grow crops including cotton, cannabis, tob ...

s of

blue gum Blue gum is a common name for subspecies or the species in ''Eucalyptus globulus'' complex, and also a number of other species of ''Eucalyptus'' in Australia. In Queensland, it usually refers to ''Eucalyptus tereticornis'', which is known elsewher ...

and other species. It is potentially threatened by competition from, and interbreeding with, a species introduced from south-eastern Australia, the closely related

long-billed corella The long-billed corella, also known as long-billed cockatoo or slender-billed corella (''Cacatua tenuirostris''), is a cockatoo native to Australia, which is similar in appearance to the little corella. This species is mostly white, with a reddis ...

, which has nearby populations established from avicultural escapes and releases. Other threats include illegal shooting and poisoning, as well as competition for nest hollows with

feral A feral (; ) animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in som ...

honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to mainland Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the ...

s. Because the corellas sometimes cause damage to crops, young trees, gardens, power lines and house fittings, the subspecies is a declared pest of agriculture. However, because it is listed as ‘rare or likely to become extinct’, it is illegal to destroy them, and damage mitigation measures must use non-lethal means.

References

{{DEFAULTSORT:corella, Muir's Muir's corella Corellas